Boyfriend made online dating profile!?

ok so I've been w my boyfriend who i met online for >2 years. we live together and all has been well. for the first year, I trusted him unconditionally. I had no worries that he would cheat on me or be unfaithful in any way. However, around a year into the relationship, give or take a couple months, I found that he had made an online dating profile in the same site that we had met on and then deleted it. this was before we were living together and i let it go because there was no picture and he hadn't sent out any messages. However, ever since then, I have found that I don't trust him like I used to even though nothing else has happened since then. However,, I find myself not being able to forget that incident and picking fights at every little thing that could be remotely construed as an indication of infidelity (ie. not texting me every second of the day). I hate that I've become like this but it truly is his own fault for that prior incident. I obviously don't want to break up, but I can't seem to figure out how to trust him again. If I don''t I fear I will drive him to being unfaithful. Any ideas?